There are so many dc pumps out there and all the impellers are pretty much the same or similar to each other. The most important part of keeping it clean and running without any issue is making sure the bearing is not stuck to the ceramic shaft and the calcium build up right behind the propeller.
Once you remove the impeller from the pump motor, please inspect the bearing inside the motor housing, make sure its there and if possible remove it. Place it to the impeller shaft, spin it or move it in and out making sure its loose. If its fit tight or you have to put some pressure or force into the movement. You need to clean the shaft and bearing. They should be loose and move freely.
Over time, the calcium also build up in the ceramic area right behind the propeller and in front of the magnet. right between the hole of the black plate.
Please follow the pictures instruction to identify the area and how to clean it.