Edit Single Product Page

Look for the content-single-product.php file which applies to your site.

See if it exists at:
wp-content/themes/<parent or child theme name>/woocommerce/content-simple-product.php
if not, look at the woocommerce version at:
wp-content/plugins/woocommerce/templates/content-simple-product.php

In the case of the default woocommerce version, note that add-to-cart is hooked at priority 30, so you can go in just below that using:

add_action( 'woocommerce_single_product_summary', 'custom_usps', 34 );
function custom_usps() {
  print '....';
}

Your function is best placed in functions.php for your child theme, though it may work with a php-snippets plugin.

print '<img src="http:// image link here ">';