They don't, but don't worry too much about it. A lot of non-native English speakers pronounce "rich" in a way that sounds like "reach". Native speakers should still understand just fine. And although "wretch" is a word you will definitely read from time to time, in daily life it's not one that many people actually use. 

If u see online dictionary they show and have audio also.
Btw ny opinion:
Rich -> e short sound
Wretch -> Wraetch
Reach -> long e sound