For hiring and assessment design look for people with at least Master degrees in Industrial Organizational psychology. PhD isn’t necessary because it’s an applied field and there aren’t many applied PhDs so work experience is more important. Most start out in public sector which is much more rigorous in their interviewing and defining roles than the private sector is. SDSU and SFSU have great programs in CA and their professors can connect you to their alumni networks. SIOP is the professional organization. IOPredict, Biddle, and RocketHire are some consulting firms.