The stamped steel impellor of the factory Magnum 5.9 water pump has a known issue with "cavitation damage" if an incorrect antifreeze mixture is used.

Years ago NASCAR cooling guru Howard Stewart of Winston Salem NC answered a question on his forum about Magnum water pumps by writing that in his opinion the GNB brand water pumps were superior.

I still have the original factory water pump on my 1995 5.9 V8 with 200,000 miles, but i have been running Evans NPG coolant for a little more than 100,000 miles.
The Evans Nonaqueous Propylene Glycol is advertised as being highly resistant to cavitation and protective against metal corrosion, but the NPG's lower "Heat Capacity" rating can only carry away about 70% of the engine heat that each gallon per minute of pure water can.