If it washes the clothes then the problem is only the buzzing noise.
If water enters the machine then the solenoid is probably operating correctly.
There is no inlet pump - water enters under the pressure in the supply pipe.
Solenoids (electrical coils) sometimes lose their mechanical integrity - the coils of wire can become loose and vibrate and this is what you may be hearing - transformers can buzz too.
The inlet solenoid is very easy to replace - you can do it yourself or have a service engineer do it for you or alternatively just live with the buzzing.
There is no need to be alarmed...