ar400 is also carbon steel and wears a ton better than MS, heck, t-1 wears better than ar plate, and then add manganese to the alloying compounds and all of a sudden, not only does it have great wear resistance, but it work hardens as well, becoming even more wear resistant..... and the cost per pound? still gonna be same if not a hair lower than stainless...

aluminum does have good wear resistance, heck, aluminum oxide is what grinding stones are made of that grind steel.... however, the softer nature of aluminum does not make it a good wear plate agent as previously asked about