LJAZ is spot on... Most "newer" pumps will run dry with no harm, however, I don't know that running dry for several hours is exactly what they mean. As LJAZ suggests, I'd load up with some freshwater and test the pump...does it come up to pressure and cut off? If it does, you should be OK. It may leak down if the impellers are worn a bit and it will cycle with no apparent usage, but, if it runs and shuts off at pressure it should be serviceable. If it does leak down the pressure and starts indiscriminately and then shuts off, you may be able to get the impeller head as a repair part. Much cheaper than replacing the whole pump.
My 2 cents, your mileage may vary...
2 Cats; J-Lo and Ragamuffin :R
2014 Thor Tuscany 40RX DP
2011 Ram 2500 Longhorn CTD HO
2011 Keystone Cougar 318SAB (now gone)
2008 FunFinder X 210WBS (Sadly gone)