If you've worn out the old sprocket with hardened steel.
And, the new one is a soft cast steel, with hollow teeth. How long will it last?
I would, of course, make sure you replace the chain at the same time you replace the sprocket. Did you replace both sprockets?
You may consider trying to make your own sprocket. Keep the old one. Either cut a new sprocket, or perhaps find a good steel sprocket, and weld it onto the base plate. Then harden and temper it.
There are some places for softer, malleable steel, but I'm not sure this is one of those places.