For typical brush noise in something like a wiper motor, the first thing would be to clean up the commutator and install new brushes (which might exceed the cost of a new motor).
If there's still noise, the best I've ever used is disc ceramic; anything from 0.1 - 0.5 microfarads, with a working voltage of at least 50VDC. Install as close to the motor housing as possible and keep the ground lead as short as possible. These aren't polarity-sensitive either lead to the motor hot lead and the other lead to ground. Note how much difference one capacitor makes and judge for yourself if you need (or want) to add another in parallel to see how much it changes things. Might change; might not.
Same for the fuel pump, but here you don't want to get into the tank. Just as close to the tank as possible. Hot lead and ground.