The cartridge generally contains all of the wear parts of the valve, and replacing it, if it is installed correctly and is the right one, generally fixes the leak and restores normal operations. If you chose an aftermarket cartridge rather than an OEM one, that may be part of the problem as could it maybe being the wrong one. Also, there could be some crud in the lines from turning the water off and dislodging things - generally, it's a good idea to turn the water on with the cartridge out to flush the lines before installing the new one.
If the body of the valve or cartridge is scratched or gouged up, it may never again seal well and would need to be replace in its entirety. It's also possible that an o-ring got dislodge when you inserted the new one. Make sure that it is lubricated with silicon plumber's grease. This will also make it easier to insert. You may have ruined the o-ring(s) if you didn't lubricate them (some come already lubricated, but not all).