A wheel hub assembly for motor vehicles, provided with a hub and a bearing unit as well as a device for detecting a vehicle parameter, having an encoder and a magnetic sensor, there being arranged between the encoder and the speed sensor an amplification device for amplifying the magnetic signal, which is stationary and has a radially outer ferromagnetic ring facing the encoder and provided with a first lug and a radially inner ferromagnetic ring facing the encoder and provided with a second lug, said first lug and second lug being arranged facing the magnetic sensor on opposite sides, the amplification device being configured to collect the magnetic flux generated by the plurality of pole pairs of the encoder via the ferromagnetic rings and concentrate it towards the magnetic sensor by means of the first lug and the second lug.