This question is very broad and hence not easily answered.
At first, beside mandatory insurances (i.e. worker's compensation if you have employees, car insurance if he company owns cars etc.), it really depends on the risks and liabilities that you might occur.
One of the questions would be, is your company a sole proprietorship or incorporated. In the first case the liability is personal and you might want to see if there are possibilities where there is a big risk of liabilities. For example, what happens if your software might damage (delete or corrupt data) at your client's computer. What are the contractual and licence agreements?
Another issue might be if you or your employees work on client's computer systems and something is damaged during the access. What are your agreements for that?
Only with this in mind, can you make a proper assessment if there is any business insurance that could be beneficial for you.