If the water pump bearings are worn to the point of allowing a tight belt to start it leaking, it's probably in need of replacement. Stop leak can/will gum up the entire cooling system eventually. It might be worse than the leak. If you used the stop leak, and then decide to replace the pump, make sure you flush the cooling system really well before refilling and returning it to service.
Mike. Comments are anecdotal or personal opinions, and worth what you paid for them.
2018 (2017 Sprinter Cab Chassis) Navion24V + 2016 Wrangler JKU (sold @ ????)
2016 Sunstar 26HE, V10, 3V, 6 Speed (sold @ 4600 miles)
2002 Roadtrek C190P (sold @ 315,000kms)