Section 193K. Wherever an insurance policy, certificate or service contract provides for reimbursement or payment for any services which may be legally performed by any person, licensed under the provisions of chapter one hundred and twelve, reimbursements or payments under such insurance policy, certificate or service contract shall not be denied because of race, color or creed nor shall any insurer make or permit any unfair discrimination against particular individuals or persons licensed under said chapter to whom reimbursement or payment would be due and payable.