Where are contacts located on Xperia P internal storage?
You need a phone with root access. The folder that usually stores the contacts is data/data/com.android.providers.contacts/databases/contacts.db As  you would imagine they are placed in a 'safer' part of the device storage. 

However, the /data folder is accessed via root directory / 

You can root the device or you can use a Contacts Contract to access the database programatically, but as a normal user you can't. 

As noted in the comments /android/data is not the same as /data