In general, in our PHAs we were concerned mainly about pump seal damage and subsequent leakage for a pump running dry. This is also the major hazard mentioned in the CCPS "Guidelines for Design Solutions for Process Equipment Failures" (1998). There is a newer edition of that book but I don't have a copy. However, it may depend on the specific pump (we generally had a maintenance person involved who knew something about the pump). It might be a good idea to discuss the specific hazards of a specific pump and service with a maintenance expert who knows something about the specific pump, and perhaps even ask the pump manufacturer.