The Workmen's Compensation Policy will not supersede the ESI schemes. It just covers one kind of benefit, i.e., accidents while on duty. However, there are many other benefits attached to ESI, including sickness benefits for about 90 days, maternity benefits such as 26 weeks of leave and medical bonuses, free medical treatment for employees as well as their family and dependents, and many more. Therefore, if you want to seek exemption from ESI, you will have to establish that the schemes and insurance offer better benefits than what the ESI Corporation provides to employees. I don't think any private insurer will be able to extend medical coverage to employees' parents who may be 80 or 90 years old!