This world is not perfectly heaven, nor perfectly hell. Almost figuratively, there is the mix of two -- but a lot less than the true thing, the other world. This world is the test ground.
The "suffering" is a case of the world, not only about good people, but if some tyrant tries to grab something, and you oppose that, you might need to fight, and that is extra work, surely. Allah is telling us not to yield to the evil, tyrants, but fight against those. Is that the "suffering" you talk about? What is the opposite, then? The opposite would be to roll over and fall to abyss, even while living in this world. (The worse, is when the tyrants try to pass as the "gods," which would hurt your other worldly status, too. Then, you have to fight.)
A hadith is telling that, prophets and saints pass through "suffering" experiences/tests.
If that is not a test (if prophets need no test), then that is perhaps to demonstrate how marvelously the high people cope up with troubles, as if there were nothing.
I think, the Quran is listing almost no suffering that is not coming to a good end, in this world, too.
Jesus (a.s.) was not killable.
Mother Mary was upheld by the baby Jesus (a.s.) talking that she was chaste.
Joseph (a.s.) became the highest official, and his father's (a.s.) eyes saw again.
Lot (a.s.) had to move from his land, but that was erhaps little loss, if the tribe was problematic. The tribe was the killed, right after Lot (a.s.) got away.
The Yasin sureh in the Quran, is telling of a few prophets and a good man, who were not relieved in this world, but martyred by their cruel tribe. That again, might have been a gift, how I told about the Lot (a.s.) having left the tribe. The Quran is quoting that man, with still the wish of having his tribe to find the right path, but in truth, that wish was presumably, futile, because next, we see that Allah kills that tribe, without giving that chance. Thus, a futile wish among that cruel tribe, would be the suffering, that Allah cut that short. In psychology terms, that is a type of reward, to get rid of the continuing trouble -- "negative re-inforcement." Thus, that man had got a this-worldly gift, too.
A hadith is telling that, a person (muslim) whose three (or, two) children die (surely, not maliciously, but without the capability of that person), that person will go to heaven [quickly].
Islam holds that, a baby is innocent. Thus, passing away, before becoming old enough to be punishable, is actually the exemption from this-worldly test. Those babies/children will go to heaven. If their parents go to hell (as non-muslims), then they will stay with Abraham (a.s.).