When you change the Water Pump, go ahead and change the Thermostat. And while going thru this, might as well drain the coolant and replace. Also do a search on "Heating core" which possibly is blocked. There are many threads on this subject. If you reverse flush the heater core and possibly use CLR to clean the heater core, then put everything back together, you will take care of your leak and probably your heating issue.
2004 Jeep Grand Cherokee Limited 2x4 4.0L
2002 Jeep Grand Cherokee Sport 2x4 4.0L
1998 Jeep Grand Cherokee Laredo 2x4 4.0L
"Three daughters, three Jeeps"