A bad thermostat, blockage in the system, or lack of proper bypass can keep the pressure on the pump too high causing early failure. Thermostats are cheap and should be replaced every couple of years anyway. If a previous pump impeller has exploded there can be peices blocking flow.
Of course these will also normally cause temperature problems.
Check alignment of the pulleys if the bearings are out on a pump.
Back-flush the block and radiator keeping an eye on the flow.
Check the plumbing to be sure no hoses have been re-routed or removed and blocked.
