SQL Server 2016 vs 2012 insert performance
Obviously it is very difficult the coincidence of having exactly the same versions in the same server but... I hope my results will help you. 
I have two different machines configured both Windows Server 2012 R2 Standard. Unfortunately they don't have the same hardware but similar:


Machine 1 (SQL Server 2016)


Processor: Intel(R) Xeon(r) CPU X5650 @2.67GHz
Microsoft SQL Server 2016 (RTM) - 13.0.1601.5 (X64)   Apr 29 2016    23:23:58   Copyright (c) Microsoft Corporation  Standard Edition     (64-bit) on Windows Server 2012 R2 Standard 6.3  (Build 9600: ) (Hypervisor)

Machine 2 (SQL Server 2012)


Processor: Intel(R) Xeon(R) CPU E5-2667 0 @ 2.9 GHz
Microsoft SQL Server 2012 - 11.0.5058.0 (X64) 
May 14 2014 18:34:29 
Copyright (c) Microsoft Corporation
Standard Edition (64-bit) on Windows NT 6.3  (Build 9600: ) (Hypervisor)



And I run 5 times in both machines the same script you have provided and obtained the following average:


2012: 9961
2016: 8971


What is almost the opposite results that you obtain. Anyway, as you have seen, my 2012 machine has better processor but the hard disk that normally is what shows the difference is the same. So, even if 2012 has better resources is a bit slower for my case.

(Sorry, please, check again, my first version had some important erratums)