The aux water pump is only used to be coolant into the heater circuit.
Make sure the aux fans are working properly, they should come on high when coolant temp reaches 107C, if it is a really hot day and the temps hold at around there I would not worry too much.
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record