Dear Mrs. Arora,
Yes, PF & ESIC shall be effect on Arrears salary..
If in case, last month you got paid less due to any circumstances, & your company paid you for those days in this month, then those days PF, ESIC (If applicable) PF & ESIC shall be attract on those days salary & same way the employer need to contribution on the same.
The difference amount of PF & ESIC need to pay in prescribe month along with your respective month salary.
There is nothing any deduction shall be attract on Leave Encasement.
If you can elaborate the case, it would be better understanding & members also advise you in appropriate way.