Body armour doesn't work too well on ribs- armour's good at stopping the thing you hit damaging you, but ribs aren't broken by the ground, they're broken by the rest of you not stopping quick enough. So a bit of padding can help a little but that's all really, and anything bulky enough to make a big difference will be unpleasant to pedal in.
Crash less, sure. Crash better is another one- I've got a reasonable tuck-and-roll, every time I've bust a rib on the bike it's because I crashed badly (mostly through sheer surprise). It's hard to learn that in adult life apparently, I did a lot of falling over and a bit of judo as a kid which did the job.