A theoretical and experimental description of the synthesis of GaP nanowire crystals by molecularbeam epitaxy on Si(111) substrates with the use of gold as a catalyst is presented. The ratio between the fluxes of materials to be deposited and the substrate temperature are varied for a short time during nanowire synthesis in order to analyze the possibility of producing nanoinclusions of different polytypes. It is established that variations in the ratio between the fluxes of materials to be deposited and in the growth temperature bring about the controllable formation of inclusions, among them are structurally cubic crystalline regions. The inclusions are several nanometers thick.