high heat or RPM you can use chome faced rings- very common on turbo builds.
BTW, moly and chrome are both a type of facing material that is put on a cast, ductile, steel, or other ring set. The cheap sets are on cast rings, then ductile, then steel. Steel rings are usually the best you can find in wide applications and there are many other coatings that can be used to fit your needs.
There really is a BIG difference between a $400 set of rings and a $40 set of rings.