InP nanowires (NWs) with an InAs insertion were grown on (001)- and (111)-oriented silicon substrates by catalyst assisted molecular beam epitaxy. To prevent the crystallization of the catalyst droplet we propose a procedure based on the realization of the switching of the elements V flux during a growth interruption. With this procedure and with the growth conditions we have used, the crystal structure of the NWs is purely wurtzite without any stacking faults. With these growth conditions, both radial and axial growths occur simultaneously and we show that the growth time of the InAs insertion could be adjusted to obtain radial quantum well emitting in the 1.3-1.6 mu m telecom band at room temperature. Published by Elsevier B.V.