My 2 cents - Water pumps do one of three things - They either leak coolant out the weeping hole, or the bearings fail causing them to fall completely apart, or they pump water. Thats all.
Grab the upper and lower radiator hoses to see if you have any flow. Bottom hose temp should be close to top hose temp if you have water flow. No flow makes the thermostat suspect.
If you overheat while driving at highway speed, the fan is not a factor. Fan is important when driving at slower speeds or stop/go traffic. Check for missing blades. if fan is new to you, check for proper rotation direction - Not all fans rotate the same direction.
Fan clutch is not that expensive and easy to change out if it is dead.
Thermostat is easy to check with pan of hot water to see if it opens.
-Mark.