I agree with the wise comments made by Mr. Dahiya and Mr. Sharma. Even if you take a corporate insurance policy, you cannot get an exemption from ESIC if your establishment and employees are within the ambit of the Act.
I can tell you from practical experience that we tried this out in one of the companies I worked with way back in the years 1998 to 2004. The company took medical insurance and applied for exemption from ESIC. As expected, ESIC rejected the application. The company contested it. The case took nearly 6 years, and eventually, the company had to pay the ESI dues with interest and penalty. I must say it added up to a 'huge' amount, and the liability reflected in the Balance Sheet. A whole lot of effort was needed to get through the process and eventually close it. The cost, executive time, and legal time we spent on it were not worth a single penny that we spent on this whole exercise.
So, my suggestion is to avoid seeking ESIC exemption in lieu of a Medical Insurance policy.
Options for Consideration
In case you accept the above, you may consider one of the two options below:
Option 1: Continue with only ESIC for your employees.
Option 2: Continue with ESIC but in addition provide extra medical insurance. Employees can choose to use it if they find ESIC facilities not to their satisfaction.
Option 2, of course, is an additional cost. However, if the people are predominantly white-collar and employee satisfaction and retention are key criteria, such as in Product IT / R&D setups, then this additional cost should not be a major constraint considering improved employee satisfaction or reduced attrition.
Those are my views for your consideration.
Thanks.