If insufficient suitable housing units are available in the community for low- and moderate-income persons and families to be displaced from a redevelopment project area, the legislative body shall assure that sufficient land be made available for suitable housing for rental or purchase by low- and moderate-income persons and families. If insufficient suitable housing units are available in the community for use by such persons and families of low and moderate income displaced by the redevelopment project, the redevelopment agency may, to the extent of that deficiency, direct or cause the development, rehabilitation or construction of housing units within the community, both inside and outside of redevelopment project areas.