A pump assembly (1) includes a pump unit (2) with an impeller (12) having a rotational axis (R), an electrical drive motor for driving the impeller (12), and a control unit for controlling the drive motor. The control unit includes a main module in a housing (15), a first detachable plug-in module (23) and a second detachable plug-in module (27). The main module is fixed to the drive motor and configured to control the drive motor. The first plug-in module (23) and the second plug-in module (27) are selectively pluggable into a first position to communicate with the main module via at least one wireless communication channel.