Assuming that this mechanism runs at ambient conditions (RT, 50%rh) and each component has same tool texture, I think the softer material should wear most. Suppliers dont always provide hardness data, but this value might be related to tensile modulus which generally is. A dry, as moulded...
Material suppliers give shrinkage values based on standard test pieces produced under ideal conditions (of course_. PE, however, varies so much depending on all the usual factors (orientation, part geometry, processing conditions (tool temp, melt temp, pressure) that values quoted have to be...