The highway commissioner is authorized to contract for insurance against any loss or liability of any officer, employee or agent of the district resulting from the wrongful or negligent act of any such officer, employee or agent while discharging and engaged in his duties and functions and acting within the scope of his duties and functions as an officer, employee or agent of the district. Such insurance shall be carried with a company authorized by the Department of Insurance to write such coverage in Illinois. Every such policy shall provide, or be endorsed to provide, that the company issuing such policy waives any right to refuse payment or deny coverage or liability thereunder, within the limits of the policy, because of any exemption the district may have from such liability. The expenditure of road funds of the district to purchase such insurance contracts constitutes a road purpose under this Act.