The face plate of a water pump can be considered another wear item. If it is scored and worn you should replace it or flip it. I keep a spare brand new cover plate on board just in case. Even at Westerbeke's exorbitant prices it was only $13.00 and again is cheap insurance. Some pumps, such as certain Oberdorfer models, have face plates with no "stamped" part numbers on them. If your face plate is worn, and the opposite side has no paint or stampings, you can simply flip it around and re-use it. My Westerbeke face plate is well embossed and can not be flipped.
Note that my paper gasket came off, except for one small chunk, in one piece.. That is not by design but rather dumb luck... Sometimes you get lucky!