The wear resistance of the alloy comes from the composition, rather than hardness. Hardness is normally a good rule of thumb, but is not near perfect for predicting wear resistance. Take MONEL K-500 for example - Not a great wear material, but can develop good hardness.
There are applications where the hardness should be similar to harder than the material mated with for optimum wear resistance, and determining replacement items.
Our book available for download shows various couplings of Nitronic 60 vs itself, as well as many other wear materials against themselves and other dissimilar couplings. Get it here.
Go here for more general information on Alloy 60 Wear Resistance.