A pump is provided with an electric motor that has a rotor. The rotor is provided with a shaft and a magnet surrounds the shaft. The magnet is connected with form fit to the shaft. A follower surrounds the shaft at least in some areas of the shaft. The follower is monolithically connected to the shaft or is connected with form fit to the shaft. The magnet is made of at least two magnet segments and the follower has projections which engage intermediate spaces formed between the magnet segments.