/**
* @snippet       WooCommerce Show Product Image @ Order-Pay Page
*/

add_filter( 'woocommerce_order_item_name', 'ts_product_image_on_order_pay', 10, 3 );

function ts_product_image_on_order_pay( $name, $item, $extra ) {

/* Return if not checkout page */

if ( ! is_checkout() ) {

return $name;

}

$product_id = $item->get_product_id();

/* Get product object */

$_product = wc_get_product( $product_id );

/* Get product thumbnail */

$thumbnail = $_product->get_image();

/* Add wrapper to image and add some css */

$image = '
'

. $thumbnail .

'
';

/* Prepend image to name and return it */

return $image . $name;

}