and also driven gear got stuck in the gear pump. but how to remove it?
Heat is going to be your friend. Localize it to the gear so as to keep as much direct heat away from the shaft and other parts. If you have your puller on with tension applied, you'll see when the part starts to separate, then you can apply more pressure at that point to the puller.
As far as the driven gear, I cannot see enough of how it's attached to anything to give you proper advice.